I used this agency . There are others out there but this one you can trust . You can do it yourself thru the Thai Embassy Consulate from home , just gotta do tons of paperwork . I found this route easier .
last year in Bangkok . Due for renewal this year . I'll be out of the country for 6 months but will need to check in a month before it expire for renewal . I got multiple entry .
my visa agent told me 20 days . I got my Non O visa for 90 days while she submitted for the retirement visa . Get multiple entry visa so you can go in and out of Thailand otherwise you will have to start the process all over again ......
I came on a tourist visa and was told I needed 20 days left in order to apply for the Non O Visa first . That was the first step then retirement visa . If it's too complicated have an agent help you . Probably you don't have enough time left ?